Liquid dispensing apparatus

ABSTRACT

A hand operated flexible bulb for use with a liquid dipensing apparatus  5 , the bulb comprises an open ended neck  2  which is securable in an air tight manner to a liquid dispensing apparatus. The flexible bulb is provided with an air inlet  6  separate from the open ended neck, the air inlet having a valve  7  associated therewith such that on application of hand pressure to the bulb, the valve closes to force air through the open ended neck and on release of pressure, the valve opens drawing air into the inlet.

[0001] This invention relates to apparatus for dispensing a fine sprayof liquid particles and more especially, but not exclusively, to liquiddispensers known as airbrushes.

[0002] GB Patent No. 2273065 describes a hand operated pump which can beconnected to a liquid dispensing apparatus with the purpose of supplyingair under pressure to a liquid source such as a pen with a nib ofabsorbent material. The hand pump described in that patent is suitablefor use with various forms of liquid dispensing apparatus. InternationalPatent Application PCT GB97/01933 describes one such liquid dispensingapparatus. Briefly, the apparatus described therein comprises a tubularcasing having at one end an inlet nozzle connectable to a source of gasunder pressure and at its other end an outlet nozzle having an orificein communication with an expansion chamber bounded by sides whichdiverge away from or converge towards the orifice, and means forlocating a liquid source including an elongate body and an absorbent nibat least partially within the casing with the nib within or in closeproximity to the nozzle orifice. The liquid source may convenientlycomprise a pen formed from a nib of absorbent material such as what iscommonly referred to as a felt tipped pen.

[0003] Another example of such a liquid dispensing apparatus isdescribed in GB Patent 2273065. Briefly this apparatus comprises aholder for releasably supporting a liquid source such as a felt tippedpen adjacent a nozzle. The nib of the pen is positioned in closeproximity to the nozzle outlet. A source of pressurised air is suppliedto the nozzle and is thereby directed onto and over the nib of the pencausing liquid absorbed therein to be dispensed in a fine particularspray in air.

[0004] The hand operated pump described in GB 2273065 comprises a bulbof flexible material formed with an open ended neck which locates overthe inlet end of the liquid dispensing apparatus. Air enters the bulbvia a nozzle in the liquid dispensing apparatus. When the liquid sourcehas been positioned adjacent the nozzle, the flexible bulb is squeezedand the air pushed out onto and over the liquid source directed by thenozzle. When the bulb is released, air is again drawn up through thenozzle of the liquid dispensing apparatus and into the bulb.

[0005] In accordance with the present invention there is provided anairbrush apparatus comprising a holder for releasably holding a liquidsource, such as a felt-tipped pen, adjacent a nozzle, the holder havingan inlet connectable to a source of gas under pressure and an outletadjacent the nozzle for dispensing the gas about the liquid source, thesource of gas comprising a hand operated flexible bulb, the bulbcomprising an open ended neck which is securable in an air tight mannerto the holder, wherein the apparatus is provided with an air inletseparate from the open ended neck of the flexible bulb, the air inlethaving a valve associated therewith such that on application of handpressure to the bulb, the valve closes to force air through the openended neck and on release of pressure, the valve opens drawing air intothe inlet.

[0006] A disadvantage of the pumps described in GB2273065 is that thereis only provided a single orifice for both the inlet and outlet of air.When the liquid source is positioned in the dispensing apparatus, thebulb is squeezed applying air under pressure to the liquid source whichis directed by the nozzle to create the fine particulate spray. When thebulb is released, pressure is equilibrated by air drawn in back throughthe nozzle to the flexible bulb. This may lead to some ink being drawnthrough the nozzle which, when the bulb is given a subsequent squeeze,larger globules of liquid may be dispensed onto the user's substrate. Afurther disadvantage with this prior art arrangement is that the bulbtakes a considerable length of time to fully expand between squeezes.These problems are alleviated by the provision of a separate air inletin accordance with the present invention.

[0007] Any suitable valve may be used for closing the air inlet, howeverthe valve is conveniently provided in the form of a closure memberslidably mounted on a shaft, the shaft projecting from the inner surfaceof the bulb adjacent one or more orifices defining the air inlet, andcomprising an end stop to prevent separation of the closure member fromthe shaft. The closure member is preferably comprised of a sheet offlexible material. In a preferred embodiment, the air inlet comprises aplurality of orifices arranged in a circumferential fashion about ashaft which projects from the inner surface of the bulb and the closuremember comprises a circular sheet of material which has an externalcircumference greater than that defined by the plurality of orifices.

[0008] The air inlet and valve may be positioned in any location remotefrom the open ended neck of the bulb, however they are preferablypositioned directly opposing the open ended neck of the bulb.

[0009] The bulb may be produced from a flexible material such as rubberwhich can be squeezed or otherwise deformed to expel air under pressuretherefrom. Preferably the surface of the bulb is provided with a nonslipsurface. The invention will now be described by way of example only withreference to the accompanying diagrammatic drawings in which;

[0010]FIG. 1 shows one embodiment of a hand operated flexible bulbaccording to the present invention;

[0011]FIG. 2 shows a cross sectional view of the embodiment of FIG. 1;

[0012]FIG. 3 shows the embodiment of FIG. 1 in combination with a liquiddispensing apparatus.

[0013] As can be seen from the Figures, the bulb comprises a continuoussurface of flexible rubber 1. To one end, the bulb 1 has an open endedneck 2. On the inner surface of the neck 2 is an annular rib 3 which issuitably configured to fit in an airtight manner around complementaryannular groove 4 on liquid dispensing apparatus 5. To the opposite end,the bulb carries an air inlet 6 with which is associated a valve 7. Theair inlet 6 comprises a small circular disc which carries a plurality ofholes in a circumferential arrangement about the centre of the disc.Protruding from the under surface of the air inlet 6 is shaft 7 b of thevalve 7 on which is slidably mounted a circular closure member 7 a of aflexible sheet material. The circumference of the closure member issubstantially equal to or slightly greater than the outer circumferenceof the air inlet 6.

[0014] The main body of the outer surface of the bulb 1 is provided witha non-slip surface 7 which aids grip of the bulb during use.

[0015] The air brush arrangement illustrated in FIG. 3 comprises a handoperated pump in accordance with the present invention. The bulb isconnected to a nozzle 8 retained within a first channel 9 of a plasticsholder 10. The holder 10 includes a second channel 11 within which isremovably mounted a sleeve 12, the sleeve 12 is retained in place with asuitable screw fixing 13. Positioned within the sleeve 12 is afelt-tipped pen 14.

[0016] The channels 9, 11 are mutually inclined so that the tip 15 ofthe pen 14 is positioned in close proximity to the nozzle outlet. Whenusing a nozzle as illustrated in FIG. 3, the pen shoulder 16 adjacentthe tip 15 is positioned against a step 17 for location purposes.

[0017] The holder 10 is designed to be held a specified distance fromthe substrate on which a fine spray of particles is to be applied.Operation of the hand pump by squeezing the bulb causes air underpressure to force the valve 7 shut and simultaneously to flow directlythrough the nozzle 8. As this compressed air passes over the tip 15 ofthe pen a fine dispersion of particles is produced on the substrate.

[0018] As the bulb is released air now at a higher pressure outside thebulb rushes in through the air inlet 6 opening valve 7 and re-inflatingthe bulb until the air pressure to the inside and outside of the bulb isequalised.

[0019] As can be seen from FIG. 3, on assembly of the liquid dispensingapparatus, the neck 2 of the bulb is forced over the inclined annularribs 18 on the outer surface of the nozzle until the end of the neckseats adjacent the end stop 19. At this point, the step of inclinedsections 18 is positioned just behind the annular rib 3 of the neck 2and ensures that, despite a build up pressure within the bulb or nozzle,the bulb is retained securely by the nozzle.

[0020] As mentioned previously, the pen 14 may be a felt-tipped pen.Alternatively it may comprise a cartridge containing a technical drawingpen, the nib of a conventional pen or a pen like cylindrical containerincluding for example, a dip tube through which a colourant such as inkcan be withdrawn. Alternatively, edible food colourants, ink basedacrylic and emulsified paints may be dispensed by means of theapparatus. A selection of sleeves 12 may be provided to enable a varietyof different liquid sources to be employed.

[0021] It will be appreciated that the foregoing is merely exemplary ofone embodiment of the pump according to the present invention and ofjust one form of liquid dispensing apparatus with which it may be used.The skilled reader will understand that modifications can readily bemade thereto without departing from the true scope of the invention.

1. An airbrush apparatus comprising a holder for releasably holding aliquid source, such as a felt-tipped pen, adjacent a nozzle, the holderhaving an inlet connectable to a source of gas under pressure and anoutlet adjacent the nozzle for dispensing the gas about the liquidsource, the source of gas comprising a hand operated flexible bulb, thebulb comprising an open ended neck which is securable in an air tightmanner to the holder, wherein the apparatus is provided with an airinlet separate from the open ended neck of the flexible bulb, the airinlet having a valve associated therewith such that on application ofhand pressure to the bulb, the valve closes to force air through theopen ended neck and on release of pressure, the valve opens drawing airinto the inlet.
 2. An airbrush apparatus as claimed in claim 1 whereinthe air inlet of the apparatus comprises one or more orifices and thevalve comprises a closure member slidably mounted on a shaft, the shaftprojecting from a surface adjacent the one or more orifices andcomprising an end stop to prevent separation of the closure member fromthe shaft.
 3. An airbrush apparatus as claimed in claim 2 wherein thevalve closure member comprises a sheet of flexible material.
 4. Anairbrush apparatus as claimed in claim 2 or claim 3 wherein the airinlet of the apparatus comprises a plurality of orifices arranged in acircumferential fashion about the shaft and the closure member comprisesa circular sheet of material having an external circumference greaterthan that defined by the plurality of orifices.
 5. An airbrush apparatusas claimed in any preceding wherein the air inlet and the valve arepositioned in the flexible bulb.
 6. An airbrush apparatus as claimed inclaim 5 wherein the air inlet is positioned directly opposite the openended neck of the flexible bulb.
 7. An airbrush apparatus as claimed inany preceding claim wherein the bulb is securable to the holder by meansof an inwardly extending annular rib provided on the inner surface ofthe flexible neck, the rib being configured to sit in an annular grooveprovided on the outer surface of the liquid dispensing apparatus.
 8. Anairbrush apparatus as claimed in any preceding claim wherein the outersurface of the bulb is provided with a non-slip covering.